Pharmacokinetics and tissue elimination of flunixin in veal calves

Am J Vet Res. 2016 Jun;77(6):634-40. doi: 10.2460/ajvr.77.6.634.

Abstract

OBJECTIVE To describe plasma pharmacokinetic parameters and tissue elimination of flunixin in veal calves. ANIMALS 20 unweaned Holstein calves between 3 and 6 weeks old. PROCEDURES Each calf received flunixin (2.2 mg/kg, IV, q 24 h) for 3 days. Blood samples were collected from all calves before the first dose and at predetermined times after the first and last doses. Beginning 24 hours after injection of the last dose, 4 calves were euthanized each day for 5 days. Plasma and tissue samples were analyzed by ultraperformance liquid chromatography. Pharmacokinetic parameters were calculated by compartmental and noncompartmental methods. RESULTS Mean ± SD plasma flunixin elimination half-life, residence time, and clearance were 1.32 ± 0.94 hours, 12.54 ± 10.96 hours, and 64.6 ± 40.7 mL/h/kg, respectively. Mean hepatic and muscle flunixin concentrations decreased to below FDA-established tolerance limits (0.125 and 0.025 μg/mL, respectively) for adult cattle by 3 and 2 days, respectively, after injection of the last dose of flunixin. Detectable flunixin concentrations were present in both the liver and muscle for at least 5 days after injection of the last dose. CONCLUSIONS AND CLINICAL RELEVANCE The labeled slaughter withdrawal interval for flunixin in adult cattle is 4 days. Because administration of flunixin to veal calves represents extralabel drug use, any detectable flunixin concentrations in edible tissues are considered a violation. Results indicated that a slaughter withdrawal interval of several weeks may be necessary to ensure that violative tissue residues of flunixin are not detected in veal calves treated with that drug.

Publication types

  • Clinical Trial

MeSH terms

  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / blood
  • Anti-Inflammatory Agents, Non-Steroidal / chemistry
  • Anti-Inflammatory Agents, Non-Steroidal / metabolism
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacokinetics*
  • Area Under Curve
  • Cattle / blood*
  • Clonixin / analogs & derivatives*
  • Clonixin / blood
  • Clonixin / chemistry
  • Clonixin / metabolism
  • Clonixin / pharmacokinetics
  • Drug Residues
  • Half-Life
  • Liver / chemistry
  • Muscle, Skeletal / chemistry
  • Muscle, Skeletal / metabolism

Substances

  • Anti-Inflammatory Agents, Non-Steroidal
  • flunixin
  • Clonixin